The present invention relates generally to the field of semiconductor manufacturing and, more specifically, to a method for forming double gated field effect transistors.
The need to remain cost and performance competitive in the production of semiconductor devices has driven the increase in device density in integrated circuits. To facilitate the increase in device density, new technologies are constantly needed to allow the feature size of these semiconductor devices to be reduced.
The push for ever increasing device densities is particularly strong in Dynamic Random Access Memory (DRAM) technologies. DRAMs are the most commonly used type of memory and are thus found in a wide variety of integrated circuit designs. DRAM is often embedded into application specific integrated circuits (ASICs), such as processors and logic devices.
Each DRAM cell contains an access transistor and a capacitor used to store the memory data. The two most common types of capacitors used to store the memory are deep trench and planar capacitors. Deep trench capacitors generally have the advantage of increased memory density, but have the disadvantage of increased process complexity and cost. For this reason, deep trench capacitors are generally only used where the large number of memory cells can justify the increased process cost. In contrast, planar capacitors can be manufactured using much simpler manufacturing techniques, and generally do not add excessive processing costs to the device. However, planar capacitors do not provide the cell density that deep trench capacitors do, and thus are limited to applications in which the number of memory cells needed is relatively low.
Thus, there is a need for improved memory structure and method of fabrication that provides for increased DRAM memory cell density without excessively increasing fabrication complexity and cost.
Accordingly, the present invention provides a memory cell and method for forming the same that results in improved cell density without overly increasing fabrication cost and complexity. The preferred embodiment of the present invention provides a fin design to form the memory cell. Specifically, a fin Field Effect Transistor (FET) is formed to provide the access transistor, and a fin capacitor is formed to provide the storage capacitor. By forming the memory cell with a fin FET and fin capacitor, the memory cell density can be greatly increased over traditional planar capacitor designs. Additionally, the memory cell can be formed with significantly less process cost and complexity than traditional deep trench capacitor designs.